Traditional vehicle electric power generating systems require the capability of managing overload conditions that can reach 20-50% or higher than the rated load connected to the system. With respect to ground vehicles, for example, conventional power supply systems typically employ an un-regulated permanent magnet generator (PMG) and active rectifier to supply high voltage direct current (HVDC). The active rectifier comprises a bidirectional pulse width modulation (PWM) converter including one or more switching devices, such as an insulated-gate bipolar transistor (IGBT), for example, which is sized to support both the rated DC bus current and the overload DC bus current. The voltage overshoot across the IGBT is caused by the energy stored in the magnetic field of the current path, such as the DC-link connections. The voltage linked to the DC-link connections can be expressed as: V=Ls×(di/dt), where Ls is the parasitic or stray inductance of DC-link connections, and di/dt is rate of fall of current. The voltage across the IGBT may exceed the maximum blocking voltage of the IGBT due to the addition of the DC-link voltage (VDC) and voltage (V) linked to the DC-link connections.
To minimize parasitic DC-link inductance, a conventional vehicle power supply typically employs a laminated bus bar system and one or more short connections between the voltage source (DC-link capacitor) and the IGBT. The increased DC bus currents, which may be caused by overload or short-circuit conditions, also typically required the implantation of snubber capacitors. Snubber capacitors are typically are mounted directly on the DC-link terminals of each IGBT to improve safety voltage margins for selected IGBT modules and DC bus capacitors. These additional snubber capacitors, however, complicate packaging design resulting in increased cost, size and or weight of the overall system.